There are several applications where conductive patterns on a substrate are subsequently plated with a metal or etched to remove a metal. Many of these conductive patterns are discontinuous, making subsequent plating difficult. Examples of such processes can be found in the printed wiring board manufacturing industry, plastic foil etching processes, or other processes where re-plating or additional electroplating of the existing discontinuous conducting patterns is desired. Discontinuous conducting patterns are used herein to describe patterns that are not electrically connected.
Current direct metallization processes use electroless plating processes to deposit a metal on conducting patterns formed on the surface of a substrate. In these methods, conductive patterns are formed lithographically using stabilized colloidal graphite, colloidal palladium, or conducting polymer films as a conducting material. When the conducting patterns are electroplated, the process is slow and the deposited metal spreads out slowly from a point of electrical contact made with the patterns. Due to this slow electroplating process it is very important to achieve a uniform electric field distribution in the electroplating bath to obtain metal deposits of uniform thickness.
Therefore, there is a need for an apparatus and a method for electroplating and/or electroetching metal layers on one or more conductive patterns formed on a substrate, that provides uniform plating and/or electroetching of the desired metal and minimizes plating of the metal on the contact cathode surface.